Numerous valving arrangements for timed operation relative to, for instance, a rotating shaft are known. For purposes of convenience, discussion of such arrangements with reference to a reciprocating piston device will be addressed.
Perhaps the most common timed valve mechanism is a poppet valve in which a tulip valve reciprocates in timed relationship to rotation of a shaft, usually by a cam shaft driven by an associated crank shaft. Though widely accepted, the poppet valve suffers several problems. A reciprocating motion with accompanying acceleration forces limits speed of operation and at high speed tends to induce wear of the valve and seat. Also, even when opened, the poppet valve obstructs to a substantial extent the opening and thus restricts flow and causes turbulence, while sudden valve closure can result in additional wear and noise.
Another simpler valving arrangement is that of a piston timed port in which a simple opening is defined, for instance, in a cylinder wall in communication with a port such that a reciprocating piston in the cylinder will open and close the port as a piston travels thereby. In addition to wear problems resulting from the rapidly moving piston, or more often piston rings, travelling over the opening, such arrangement is inappropriate for use in the ubiquitous four stroke Otto-cycle engine in that the timing of such device usually causes a valve to open on the upstroke of the piston to remain open through a complete downstroke and somewhat into the following upstroke. Thus, a valving device that opens at a fixed position in each stroke is clearly inappropriate and inflexible.
Rotary valves in which, in the common instance, a fixed cylinder having an opening defined therethrough is contained in or contains a rotating cylinder having a complementary opening therethrough such that as the rotating cylinder passes through an aligned arrangement between the opening therein and the fixed cylinder opening flow occurs, has certain apparent advantages. Reciprocating parts are avoided. However, because of the extensive travel between various portions of the valving mechanism, wear and accordingly sealing shortcomings have often developed when such rotary valves are used. In a related arrangement, a disc rotating adjacent an opening again involves substantial surface to surface wear as the disc rotates through each valve cycle.
An unusual valving mechanism is described in U.S. Pat. No. 4,325,331 issued Apr. 20, 1982 to Frederick L. Erickson. As particularly well shown in FIGS. 30 through 32, a combination of edge surfaces of a reciprocating piston and orbiting piston are used to effect a variation of the above described piston timed port arrangement. Such configurations clearly are restricted to timing rate, duration and/or location of the parts.
U.S. Pat. Nos. 1,972,302 and 3,736,07B issued Sept. 4, 1934 to Hutchinson, Jr. and May 29, 1973 to Read et al., respectively, show the use of a rotating member adjacent a fixed member for bringing ports in the rotating and fixed members into and out of communication with one another. However, there is apparently no teaching of port means configured for conditioned flow through the device for reduction of turbulence, noise and/or wear due to impacts occasioned by sudden opening and closing of ports.
Numerous other valving arrangements have been proposed, but usually with the disadvantages or combinations of disadvantages discussed above resulting from reciprocating or rotary movement between the different valve components.